Simple analog pulse

Hello.
I have a relay in a usb box which is triggered by software (not my box or software). The realy closure time is not consistent depending on how busy the computer is. I think there must be a really simple way of making a consistent pulse using a transistor/capacitor resistor thing but it isn't really my thing. This has to be real easy surely. I just need a consistent switch closure of about .2 of a second regardless of how long the relay is closed. Once the realy opens again that would reset the circuit. Any help?

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555 timer